Lemon Tea Cookies (Dad's Favorite)

1 2/3 cups flour
1/3 cup powder sugar
1 cup butter or margarine softened
1 teaspoon vanilla
Filling:
1 egg beaten
2/3 cup sugar
2-3 teaspoon grated lemon peel
1 teaspoon cornstarch
3 Tablespoons lemon juice (1 lemon)
1 Tablespoon butter
Coconut and powder sugar
(Lightly spoon flour & measure)
In medium bowl combine first four ingredients and blend well. Chill dough. Heat oven to 350. Shape dough into 1 inch balls. Place 2 inches apart on ungreased cookie sheet. Press a thumb print in center of each cookie. Bake 8 to 10 minutes until lightly browned. Cool. Combine filling ingredients except coconut and powder sugar. Cook over low heat stirring constantly until smooth and thickened. Cool. Top each cookie with about 1/4 teaspoon filling. Sprinkle with coconut and or powdered sugar. Store single layered and cover loosely.